Panametrics CGA 351, User Manual, Page: 26 / 119

Chapter 3.
20 CGA 351 User’s Manual
3.1.5.3 Using the Auto Range Feature
The Auto Range feature includes three unit types:
• ARng (Auto Range %): the ratio of the current oxygen reading to the currently active Auto Range, expressed as a
percentage
• AR-A (Auto Range Alarm A): automatically set to a value of
0 or 1
• AR-B (Auto Range Alarm B): automatically set to a value of
0 or 1
As an example of how these units work with the default values listed in Table 64 on page 43, consider a situation
where the current oxygen reading is 7.5% . The Auto Range feature would select the current active range as Range 3 in
the table. Then,
This means that the current oxygen reading represents 75% of the currently active Auto Range. In addition to the
ARng value calculated above, AR-A = 0 and AR-B = 1 , as shown in the table.
After programming the Auto Ranges, the CGA 351 must be configured to properly handle the Auto Range output. To
accomplish this, the following outputs must be reprogrammed:
•
Alarm A and Alarm B
• 4-20 mA analog output
ARng
%O2
 
AR Zero
 
–
AR Span
 
AR Zero
 
–
---------------------------------------------------------- 100
 75% = =